CDKL5/STK9 mutations have been demonstrated in a broad spectrum of phenotypes, including X-linked infantile spasms (ISSX) or West syndrome, infantile epileptic encephalopathy, Otohara syndrome, Atypical Rett syndrome with infantile spasms or the Hanefeld variant, Mild mental retardation and autism, and Angelman syndrome-like phenotype. CDKL5/STK9 mutations are X-linked and appear to be less common in males than females, though few male patients have been studied. The CDKL5/STK9 gene codes for the cyclin-dependent kinase-like 5 or serine threonine kinase 9 protein (OMIM #300203) and is located at Xp22. We offer full gene sequencing of all \coding exons and intron/exon boundaries of CDKL5 by direct sequencing of amplification products in both the forward and reverse directions. CDKL5 sequencing is also available as part of our Rett/Atypical Rett syndrome panel, our Early Infantile Epileptic Encephalopathy (EIEE) panel, our X-Linked Non-Syndromic Intellectual Disability Panel and our Comprehensive Non-Syndromic Intellectual Disability panel. Please see our information sheet for more details. Contact the International Foundation for CDKL5 Research (www.cdkl5.com) for more information and support.